delete dcs-batch-helper

The idea of it was to start a new batch instance for long/expensive
queries. At the moment, we can just handle these queries with our normal
stack, since we don’t get a lot of queries and the performance
degradation is not a problem anymore with the new architecture/hardware.
delete dcs-debmirror

In the new architecture, we don’t need fast mirror clones anymore.
Instead, packages are fed to dcs-package-importers running on each
machine by the dcs-feeder.

In case you want to fork/revive dcs-debmirror, note that it has a bug
where it doesn’t handle errors (e.g. connection closed by peer)
correctly, so if the mirror clone fails, you’d need to restart it at the
moment.
delete dcs-index

Instead of creating one big index shard (which is what this tool did),
we now create lots of small index files and merge them together (in the
dcs-package-importer).
delete dcs-unpack

Packages are now unpacked in dcs-package-importer.